SharePlay for anyone who didn't know is a PS4 feature that allowed you to let friends remotely play a game on your console.

By removing this support from P.T. means nobody else can play your downloaded copy from their console over the net.

As one poster explains it could also have been an automatic casualty of P.T. 's removal from the store:"It's probably related to being removed from the store, because IIRC any game you Shareplay is added to your library feed, which you can then click to go to its store page and purchase the title."